Methyl-tertiary-butyl-ether (MTBE) misclassified

Area of Science:

• Toxicology
• Environmental Health
• Public Health Policy

Background:

• Methyl-tertiary-butyl-ether (MTBE) was introduced in 1992 as a fuel additive to reduce carbon monoxide emissions.
• Concerns arose regarding MTBE's potential health effects, particularly its carcinogenicity.
• The National Toxicology Program (NTP) reviewed data on MTBE's health impacts.

Purpose of the Study:

• To evaluate the carcinogenicity of MTBE based on data presented to the NTP Board of Scientific Counselors.
• To assess whether MTBE meets the criteria for classification as a "Reasonably anticipated to be a human carcinogen."
• To advocate for a review of NTP's decision-making process regarding MTBE's carcinogenicity.

Main Methods:

• Presentation of toxicological data on MTBE exposure in CD1 mice at an NTP Board of Scientific Counselors meeting.
• Discussion and voting on the classification of MTBE as a potential human carcinogen.
• Analysis of NTP's established rules and procedures for carcinogenicity assessment.

Main Results:

• Data indicated increased incidences of liver tumors, renal adenomas, testicular cancers, lymphomas, and leukemia in exposed mice.
• The NTP Board narrowly defeated a motion to classify MTBE as "Reasonably anticipated to be a human carcinogen" (6-5 vote).
• The decision was noted to contravene established NTP procedures for carcinogenicity assessment.

Conclusions:

• The NTP Board's decision on MTBE's carcinogenicity classification warrants reconsideration.
• Public health policy necessitates a review of MTBE using established criteria for carcinogen listing.
• Millions of Americans exposed to MTBE deserve an unbiased evaluation of its carcinogenic potential.